1. Field of the Invention
The present invention relates to a divisional type flywheel device as a torsional damper, hereinafter referred to as a torsional damper type flywheel device. More particularly, the present invention relates to a torsional damper type flywheel device having a deceleration side spring constant which is less than an acceleration side spring constant thereof.
2. Description of the Prior Art
Prior art torsional damper type flywheel devices, which include drive side and driven side flywheels connected by a plurality of springs, have the same spring constant and therefore the same torque capacity for the acceleration side and the deceleration side thereof. However, in a flywheel device coupled to an automobile engine, the deceleration side torque capacity need not be as great as the acceleration side torque capacity and can be as small as to at most bear an engine brake torque.
A torsional damper type flywheel device having the same, great spring constant for the acceleration and deceleration sides thereof has the disadvantage that the flywheel device may cause a vibration of great amplitude when an unexpected, great torque acts on the flywheel device, for example, at the time of ignition miss, because the vibration is amplified on both the acceleration and deceleration sides. Also, the unnecessarily high deceleration side torque capacity requires that a relatively great space be provided for rotation of the torque transmitting arms on the deceleration side as well as on the acceleration side thereof, which restricts the space for arranging other components and makes it difficult to design a compact flywheel device.